Intraspecific trait variability and genetic diversity in the adaptive strategies of serpentine and non-serpentine populations of Silene paradoxa L

Aims: We investigated whether individuals of Silene paradoxa L., grown in serpentine and non-serpentine soils, displayed variation in functional traits and adaptive strategies together with a differentiation of the gene pool. We hypothesised that individuals growing in serpentine sites may be exposed to a higher degree of stress, resulting in measurable differences in leaf traits and adaptive strategies, and as well that the differences in the soil type were associated with a genetic process of differentiation. Methods: We analysed a specific set of leaf functional traits of populations of S. paradoxa grown on serpentine and non-serpentine soils. Furthermore, DNA-fingerprinting techniques were used to further dissect the emergence of genetic processes of differentiation linked to the different soil types. Results: We detected a relevant intraspecific trait variation in S. paradoxa, with the populations from serpentine sites significantly polarised towards the stress-tolerant adaptive strategy. This polarisation came with a shift in gene pool selection, even if we did not detect quantitative differences in the genetic diversity or evidence of genetic drift. Conclusions: The results indicate that particular edaphic conditions acted on the selection of some regions of the species’ genome, independently of the site, with various portions of the genome being exclusive to or prevalent in the serpentine or non-serpentine populations.